I have read there are three more dams to be removed from the Yellow Breeches creek. How closely related to conservation are the removal of these dams? How closely related to dangers of low head dams are the removal of these dams. I live in the area and fish the Yellow Breeches many times a year. In the past couple of years, there have been accidents and deaths related to the low head dams. According to the map http://www.americanrivers.org/assets/ ... /yellow-breeches-dams.pdf there are 24 dams. I am just curious what you think, removal of dams to support conservation or removal of dams for public safety?

In my view they should notch the dams to an elevation that is low enough to get rid of large warming impoundments, but remains high enough to create normal-sized pools (for the size of the stream) so there is a good flow through the pool, i.e. the sort of riffle-pool arrangement that you would find on natural streams.

All these stream/floodplain systems are very highly altered. So the expectation that totally removing the dams will result in a return to normal stream structure is not realistic. What often results are straight, shallow stream reaches with little holding water for fish.

So, you should be conservative about total removal of artificial habitat-forming structures on highly altered streams. In many cases old dams can create pool habitat both above and below the dam. There's not a problem if the pools are reasonably sized, rather than large ponds. Natural trout streams have pools and pool habitat is very important in sustaining fish populations.

Most dam removals sites that I have seen in the Mid-Atlantic Piedmont are done in the name of conservation but in reality fail to be an adequate conservation method. The floodplains in this region are very different from what existed naturally 400 years ago. Most floodplains did not have one channel but rather consisted of multiple small, shallow channels intermixed with wetlands and beaver ponds. It is unknown whether these floodplains were a product of beaver populations or whether the beaver populations flourished due to the floodplains that existed. Either way, research has shown that trout in moderate to steep gradient streams benefit from having beaver dams. Trout in low gradient streams do not benefit from beaver dams. In some cases, low head dams are small to begin with or have been lowered from their original height. If the stream gradient is correct, these structures may be of benefit to the trout populations. Another factor to consider is that dam removal often results in significant stream bed sedimentation downstream over the course of many years. Basically, the sediment that is stored in the dam reservoir is slowly washed downstream until it finds the next reservoir or culvert (ex: bridge) and is then deposited there. The biggest problem I have with low head dam removal is the failure to properly address the erosion following the removal. TU is in the habit of removing dams in the name of conservation; however, they removed the dam and do very little to prevent erosion. They call it a success but in reality all they are doing is creating a very unstable system. Most streams in the Piedmont have never transported gravel; however, most streams that have a history of dam removal or dam breech have extensive gravel bars. Pick up a handful of gravel sometime and look at it. It has sharp, pointed margins. Systems that transport gravel tend to have rounded gravel. When a dam is removed and the result is gravel bars with non-rounded gravel, that is a pretty good indicator that the system is far from stable. Sure other factors like development and storm water runoff come into play, but the main problems lies in the fact that the Piedmont (and most other) floodplains are drastically altered. Unless we want to shell out millions to correctly improve floodplains post-dam removal, then I would only support dam removal for safety.

crs5942 wrote:Most dam removals sites that I have seen in the Mid-Atlantic Piedmont are done in the name of conservation but in reality fail to be an adequate conservation method. The floodplains in this region are very different from what existed naturally 400 years ago. Most floodplains did not have one channel but rather consisted of multiple small, shallow channels intermixed with wetlands and beaver ponds. It is unknown whether these floodplains were a product of beaver populations or whether the beaver populations flourished due to the floodplains that existed. Either way, research has shown that trout in moderate to steep gradient streams benefit from having beaver dams. Trout in low gradient streams do not benefit from beaver dams. In some cases, low head dams are small to begin with or have been lowered from their original height. If the stream gradient is correct, these structures may be of benefit to the trout populations. Another factor to consider is that dam removal often results in significant stream bed sedimentation downstream over the course of many years. Basically, the sediment that is stored in the dam reservoir is slowly washed downstream until it finds the next reservoir or culvert (ex: bridge) and is then deposited there. The biggest problem I have with low head dam removal is the failure to properly address the erosion following the removal. TU is in the habit of removing dams in the name of conservation; however, they removed the dam and do very little to prevent erosion. They call it a success but in reality all they are doing is creating a very unstable system. Most streams in the Piedmont have never transported gravel; however, most streams that have a history of dam removal or dam breech have extensive gravel bars. Pick up a handful of gravel sometime and look at it. It has sharp, pointed margins. Systems that transport gravel tend to have rounded gravel. When a dam is removed and the result is gravel bars with non-rounded gravel, that is a pretty good indicator that the system is far from stable. Sure other factors like development and storm water runoff come into play, but the main problems lies in the fact that the Piedmont (and most other) floodplains are drastically altered. Unless we want to shell out millions to correctly improve floodplains post-dam removal, then I would only support dam removal for safety.

Please qualify this statement with some examples of actual projects.

Posted on: 2010/3/11 12:25

_________________Don't hit me with them negative waves so early in the morning. Think the bridge will be there and it will be there. It's a mother, beautiful bridge, and it's gonna be there. Ok?

The few that I am most familiar with are the Pumping Station dam on Hammer Creek, the Millport Conservancy Dam on Lititz Run, and Bender Mill dam on West Branch Little Conestoga Creek, all of which are in Lancaster County. I know that at least two were removed within the past 10 years. Hammer Creek was an excellent example because basically nothing was done to prevent erosion. The dam reservoir sediments were washed downstream to the estuary and slack water of Speedwell Forge Lake. Unfortunately, sediment has buried most of the stream gravel downstream from the dam removal site. I do not know of any stream surveys that have been done but I used to catch many wild brook and brown trout downstream from the dam removal site. I have not caught any in the past few years. Maybe it is just bad luck; however, I would wager that at least 75% of stream bank erosion in the Piedmont is directly related to the previous removal of a dam. Some of the erosion that exists today is from dams that were breeched in the 70s. 40 years and the system has still not reached equilibrium. Certainly storm water runoff plays a role, but the big player in erosion is the sediment that was stored in the reservoir. Huge boulders, rock vanes, and natural stream channel design help to slow erosion on Piedmont streams but they do not prevent it. Unfortunately, it is impossible to fix most of our flood plains due to modern infrastructure or financial limitations. That is why I think there are some cases where dam removal should not be done unless it is absolutely necessary. Hammer Creek is much wider and shallower than it was before the dam removal. IMO, the fishing has not improved and may have gotten slightly worse. There are wild trout in the waters upstream from the old dam, but they were there prior to the dam removal.

The big picture is that most of the sediment going into the Chesapeake Bay is a direct result of erosion in old dam reservoirs. The erosion does not occur until the dam is breeched or lowered. The solution is simple, removed the sediment and put it back on the hill tops where it came from hundreds of years ago. Unfortunately, it is extremely expensive and in some cases impossible due to infrastructure limitations like bridges, sewer lines, parking lots, etc. 10 years ago PFBC and PA TU seemed to be on a dam removing binge. I think they are slowly starting to understand the cost:benefit with regard to low head dam removal, especially in the Piedmont. I am not opposed to dam removal; however, I do not believe that removal is always in the best interest of fisheries conservation due to the fact that there is not enough money spent to prevent downstream sedimentation. I will say that it is remarkable that some of the best wild trout streams in the Piedmont are severely impaired. Valley Creek, Letort, Codorus, Spring Creek, and the upper sections of Penns Creek are all excellent examples of wild trout fisheries that flow through reservoir sediments.

The reality is that if most of the Piedmont streams were restored to their native state it would drastically alter the valley bottoms and fly-fishing tactics would need to be completely different. Most limestone or spring creeks that exist today were more like multiple channel marshlands prior to European arrival. Dense, wetland thickets with shallow cold water and deeper pools behind beaver dams. The first thing that Europeans did was channelize the wetlands, drain the valley bottoms, and burn the thickets. After agriculture was established on higher ground, mills and dams were built, the valleys flooded, and the native floodplains buried under 3-20 feet of sediment. The entire floodplain system in the Piedmont (and much of the state) is completely the result of human manipulation on the landscape. If we pull a dam out of the system, the only way to make it function naturally is remove everything else that we have put into the system. This is why no dam removal will ever be completely successful and why most do not even come close to being successful. Most people still believe that natural stream channel design is appropriate for use on mid-Atlantic Piedmont streams; however, this model was created using western river systems that transport gravel and thus has no merit in Piedmont streams that are not suppose to transport gravel. Science is slowly changing floodplain restoration protocol in the Mid-Atlantic Piedmont. Unfortunately, significant change will probably not come before Pennsylvania gets hit with billions in fines due to our pollution of the Chesapeake Bay.

A couple of years ago Sharrer's Mill dam was removed on the Conewago creek. Before the removal of the dam, the water held trout, small and large mouth bass, rock bass, sunfish, suckers, carp and it was an area frequented by fisherman. Now, that section of the creek holds no fish.